A new study suggests that many infants dying suddenly and unexpectedly in all kinds of sleep environments have underlying brainstem abnormalities.
The researchers, led by Hannah Kinney, professor of pathology at Harvard Medical School and Boston Children’s Hospital, also point to the need to detect and treat this underlying vulnerability early. They report their findings in the December issue of Pediatrics.
The investigators have shown over the past two decades that infants who die suddenly, unexpectedly and without explanation— whose deaths are generally attributed to sudden infant death syndrome (SIDS)— have differences in brainstem chemistry that set them apart from infants dying of other causes.
These abnormalities impair brainstem circuits that help control breathing, heart rate, blood pressure and temperature control during sleep and, the researchers believe, prevent sleeping babies from rousing when they rebreathe too much carbon dioxide due to inadequate ventilation, breathe too little oxygen or become overheated from overbundling.
At the same time, epidemiologic studies have shown that infants dying suddenly and unexpectedly are often found sleeping face down with their face in the pillow, or sleeping next to an adult in a bed—environments that have the potential to lead to smothering and death by asphyxia.
In the new study, Kinney and colleagues asked if all these infants are truly normal. They re-examined their data, reviewing the cases of 71 infants who died suddenly and unexpectedly, were autopsied at the San Diego County Medical Examiner’s office from 1997 to 2008 and had brainstem samples available for analysis. The researchers grouped the infants according to sleep circumstances— those that were considered likely to generate asphyxia and those that were not— based upon death-scene investigation reports.